Conventionally, a vehicle-to-vehicle communication is used to transmit information from one vehicle to the other vehicle, and the transmitted information is used on the receiving vehicle for determining a relative position of the other vehicle. For example, Japanese Patent Laid-Open No. 2010-244290 (JP '290) discloses a technique that determines whether the other vehicle is an oncoming vehicle relative to the subject vehicle or not, based on the position information and the travel information of the other vehicle and the position information and the travel direction of the subject vehicle.
In the technique of JP '290, the position information of only one point is transmitted. However, if such technique is extended, travel locus information of a vehicle including the position information of multiple points may be transmitted at one time (i.e., single transmission of information) through vehicle-to-vehicle communication, for determining the relative position of the vehicle and/or recognizing behaviors of the other vehicles in for example, a convoy travel of vehicles. That is, in a convoy of vehicles the relative positions and/or behaviors of the other vehicles relative to a subject vehicle can be recognized by the exchange of information through vehicle-to-vehicle communication, for securely organizing the convoy.
However, in such information transmission/exchange scheme, the transmitted position information of multiple points may cause a congestion of information if there are many vehicles densely/closely populated on the road that are transmitting, for example, travel locus information through vehicle-to-vehicle communication at substantially the same time.